The present invention relates to a system for measuring crank angle for an internal combustion engine.
In recent years, various electronic control systems have been provided for electrically controlling engine speed, the advance of the ignition timing, and other parameters in dependency on conditions of engine operation. In order to carry out such electrical controls, it is necessary to meausre the crank angle of the engine. Conventional systems for measuring the crank angle perform various types of direct measuring methods. One of the methods comprises a gear rotated by the crankshaft of the engine and an electromagnetic transducer for measuring the position of a tooth of the gear. Another method comprises a rotary disc having a slit, which rotates in synchronism with the crankshaft, and a photoelectric transducer having a photoelectric element for optically measuring the position of the slit. Each of these systems necessarily is provided with a rotary member and a transducer for measuring the angular position of the rotary member. Therefore, space for installing such members must be provided in the engine and the position of the space is limited within a specific area.